It is known to provide an aircraft with a health and usage monitoring system (HUMS). A HUMS can include one or more sensors arranged to monitor parts of the aircraft to determine for example whether the parts have been subjected to mechanical loads exceeding a predetermined acceptable limit.
One type of HUMS is known in the art as an integrated vehicle health monitoring system (IVHMS), also known as an aircraft condition monitoring system (ACMS). An IVHMS is an integral part of an aircraft, which is installed at the point of aircraft manufacture.
It is also known to provide a HUMS upgrade which can be retrofitted to an in-service aircraft by interfacing the HUMS with the aircraft IVHMS and/or avionics system to receive trigger systems from the IVHMS and/or avionics system.
The present inventor has identified that HUMS can be improved in terms of one or more of the following aspects:                complexity;        weight;        degree of interference with aircraft systems; and        suitability for retrofitting to in-service aircraft.        